Auto merge of #106320 - jyn514:revert-merge-check, r=jyn514

Revert "Auto merge of #105058 - Nilstrieb:no-merge-commits, r=jyn514"

This reverts commit 4839886f0abe208ab8f2bb73a3076a59fe2ab60c, reversing changes made to ce85c98575e3016cf2007d90a85be321e592aa96.

Fixes https://github.com/rust-lang/rust/pull/106232#issuecomment-1368144655.

r? `@jyn514`

18 files changed, 60 insertions, 195 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2770bded30a..23d3e71424b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -71,11 +71,6 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 2
-      - name: "checkout the `master` branch for tidy"
-        uses: actions/checkout@v3
-        with:
-          ref: master
-          fetch-depth: 1
       - name: configure the PR in which the error message will be posted
         run: "echo \"[CI_PR_NUMBER=$num]\""
         env:
@@ -490,11 +485,6 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 2
-      - name: "checkout the `master` branch for tidy"
-        uses: actions/checkout@v3
-        with:
-          ref: master
-          fetch-depth: 1
       - name: configure the PR in which the error message will be posted
         run: "echo \"[CI_PR_NUMBER=$num]\""
         env:
@@ -610,11 +600,6 @@ jobs:
         uses: actions/checkout@v3
         with:
           fetch-depth: 2
-      - name: "checkout the `master` branch for tidy"
-        uses: actions/checkout@v3
-        with:
-          ref: master
-          fetch-depth: 1
       - name: configure the PR in which the error message will be posted
         run: "echo \"[CI_PR_NUMBER=$num]\""
         env:
diff --git a/Cargo.lock b/Cargo.lock
index 79c70ee31c7..9581099c210 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -260,10 +260,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "build_helper"
-version = "0.1.0"
-
-[[package]]
 name = "bump-stage0"
 version = "0.1.0"
 dependencies = [
@@ -5308,7 +5304,6 @@ dependencies = [
 name = "tidy"
 version = "0.1.0"
 dependencies = [
- "build_helper",
  "cargo_metadata 0.14.0",
  "ignore",
  "lazy_static",
diff --git a/Cargo.toml b/Cargo.toml
index ce08d4edb56..1cec4a84480 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -4,7 +4,6 @@ members = [
   "library/std",
   "library/test",
   "src/rustdoc-json-types",
-  "src/tools/build_helper",
   "src/tools/cargotest",
   "src/tools/clippy",
   "src/tools/clippy/clippy_dev",
diff --git a/src/bootstrap/Cargo.lock b/src/bootstrap/Cargo.lock
index 4a0ba592577..efe8ae3169f 100644
--- a/src/bootstrap/Cargo.lock
+++ b/src/bootstrap/Cargo.lock
@@ -36,7 +36,6 @@ dependencies = [
 name = "bootstrap"
 version = "0.0.0"
 dependencies = [
- "build_helper",
  "cc",
  "cmake",
  "fd-lock",
@@ -72,10 +71,6 @@ dependencies = [
 ]
 
 [[package]]
-name = "build_helper"
-version = "0.1.0"
-
-[[package]]
 name = "cc"
 version = "1.0.73"
 source = "registry+https://github.com/rust-lang/crates.io-index"
diff --git a/src/bootstrap/Cargo.toml b/src/bootstrap/Cargo.toml
index 22ceeca941e..fafe82a9c12 100644
--- a/src/bootstrap/Cargo.toml
+++ b/src/bootstrap/Cargo.toml
@@ -30,7 +30,6 @@ path = "bin/sccache-plus-cl.rs"
 test = false
 
 [dependencies]
-build_helper = { path = "../tools/build_helper" }
 cmake = "0.1.38"
 fd-lock = "3.0.8"
 filetime = "0.2"
diff --git a/src/bootstrap/format.rs b/src/bootstrap/format.rs
index 64ae3fe0db9..1d57c6ecbbb 100644
--- a/src/bootstrap/format.rs
+++ b/src/bootstrap/format.rs
@@ -2,7 +2,6 @@
 
 use crate::builder::Builder;
 use crate::util::{output, program_out_of_date, t};
-use build_helper::git::get_rust_lang_rust_remote;
 use ignore::WalkBuilder;
 use std::collections::VecDeque;
 use std::path::{Path, PathBuf};
@@ -101,6 +100,35 @@ fn get_modified_rs_files(build: &Builder<'_>) -> Option<Vec<String>> {
     )
 }
 
+/// Finds the remote for rust-lang/rust.
+/// For example for these remotes it will return `upstream`.
+/// ```text
+/// origin  https://github.com/Nilstrieb/rust.git (fetch)
+/// origin  https://github.com/Nilstrieb/rust.git (push)
+/// upstream        https://github.com/rust-lang/rust (fetch)
+/// upstream        https://github.com/rust-lang/rust (push)
+/// ```
+fn get_rust_lang_rust_remote() -> Result<String, String> {
+    let mut git = Command::new("git");
+    git.args(["config", "--local", "--get-regex", "remote\\..*\\.url"]);
+
+    let output = git.output().map_err(|err| format!("{err:?}"))?;
+    if !output.status.success() {
+        return Err("failed to execute git config command".to_owned());
+    }
+
+    let stdout = String::from_utf8(output.stdout).map_err(|err| format!("{err:?}"))?;
+
+    let rust_lang_remote = stdout
+        .lines()
+        .find(|remote| remote.contains("rust-lang"))
+        .ok_or_else(|| "rust-lang/rust remote not found".to_owned())?;
+
+    let remote_name =
+        rust_lang_remote.split('.').nth(1).ok_or_else(|| "remote name not found".to_owned())?;
+    Ok(remote_name.into())
+}
+
 #[derive(serde::Deserialize)]
 struct RustfmtConfig {
     ignore: Vec<String>,
diff --git a/src/bootstrap/lib.rs b/src/bootstrap/lib.rs
index d44b96cfb99..5ea41d10bc8 100644
--- a/src/bootstrap/lib.rs
+++ b/src/bootstrap/lib.rs
@@ -113,7 +113,6 @@ use std::path::{Path, PathBuf};
 use std::process::Command;
 use std::str;
 
-use build_helper::ci::CiEnv;
 use channel::GitInfo;
 use config::{DryRun, Target};
 use filetime::FileTime;
@@ -122,7 +121,7 @@ use once_cell::sync::OnceCell;
 use crate::builder::Kind;
 use crate::config::{LlvmLibunwind, TargetSelection};
 use crate::util::{
-    exe, libdir, mtime, output, run, run_suppressed, symlink_dir, try_run_suppressed,
+    exe, libdir, mtime, output, run, run_suppressed, symlink_dir, try_run_suppressed, CiEnv,
 };
 
 mod bolt;
diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index bdc81b07b8d..4e503dfe864 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -24,8 +24,6 @@ use crate::util::get_clang_cl_resource_dir;
 use crate::util::{self, exe, output, t, up_to_date};
 use crate::{CLang, GitRepo};
 
-use build_helper::ci::CiEnv;
-
 #[derive(Clone)]
 pub struct LlvmResult {
     /// Path to llvm-config binary.
@@ -219,7 +217,7 @@ pub(crate) fn is_ci_llvm_available(config: &Config, asserts: bool) -> bool {
         return false;
     }
 
-    if CiEnv::is_ci() {
+    if crate::util::CiEnv::is_ci() {
         // We assume we have access to git, so it's okay to unconditionally pass
         // `true` here.
         let llvm_sha = detect_llvm_sha(config, true);
diff --git a/src/bootstrap/util.rs b/src/bootstrap/util.rs
index 8ce9a9ce38c..58220783228 100644
--- a/src/bootstrap/util.rs
+++ b/src/bootstrap/util.rs
@@ -255,6 +255,35 @@ pub enum CiEnv {
     GitHubActions,
 }
 
+impl CiEnv {
+    /// Obtains the current CI environment.
+    pub fn current() -> CiEnv {
+        if env::var("TF_BUILD").map_or(false, |e| e == "True") {
+            CiEnv::AzurePipelines
+        } else if env::var("GITHUB_ACTIONS").map_or(false, |e| e == "true") {
+            CiEnv::GitHubActions
+        } else {
+            CiEnv::None
+        }
+    }
+
+    pub fn is_ci() -> bool {
+        Self::current() != CiEnv::None
+    }
+
+    /// If in a CI environment, forces the command to run with colors.
+    pub fn force_coloring_in_ci(self, cmd: &mut Command) {
+        if self != CiEnv::None {
+            // Due to use of stamp/docker, the output stream of rustbuild is not
+            // a TTY in CI, so coloring is by-default turned off.
+            // The explicit `TERM=xterm` environment is needed for
+            // `--color always` to actually work. This env var was lost when
+            // compiling through the Makefile. Very strange.
+            cmd.env("TERM", "xterm").args(&["--color", "always"]);
+        }
+    }
+}
+
 pub fn forcing_clang_based_tests() -> bool {
     if let Some(var) = env::var_os("RUSTBUILD_FORCE_CLANG_BASED_TESTS") {
         match &var.to_string_lossy().to_lowercase()[..] {
diff --git a/src/ci/github-actions/ci.yml b/src/ci/github-actions/ci.yml
index d3b07419486..d33396dcc80 100644
--- a/src/ci/github-actions/ci.yml
+++ b/src/ci/github-actions/ci.yml
@@ -103,12 +103,6 @@ x--expand-yaml-anchors--remove:
         with:
           fetch-depth: 2
 
-      - name: checkout the `master` branch for tidy
-        uses: actions/checkout@v3
-        with:
-          ref: master
-          fetch-depth: 1
-
       # Rust Log Analyzer can't currently detect the PR number of a GitHub
       # Actions build on its own, so a hint in the log message is needed to
       # point it in the right direction.
diff --git a/src/tools/build_helper/Cargo.toml b/src/tools/build_helper/Cargo.toml
deleted file mode 100644
index 99f6fea2ecf..00000000000
--- a/src/tools/build_helper/Cargo.toml
+++ /dev/null
@@ -1,8 +0,0 @@
-[package]
-name = "build_helper"
-version = "0.1.0"
-edition = "2021"
-
-# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
-
-[dependencies]
diff --git a/src/tools/build_helper/src/ci.rs b/src/tools/build_helper/src/ci.rs
deleted file mode 100644
index 9f113c72b93..00000000000
--- a/src/tools/build_helper/src/ci.rs
+++ /dev/null
@@ -1,40 +0,0 @@
-use std::process::Command;
-
-#[derive(Copy, Clone, PartialEq, Eq, Debug)]
-pub enum CiEnv {
-    /// Not a CI environment.
-    None,
-    /// The Azure Pipelines environment, for Linux (including Docker), Windows, and macOS builds.
-    AzurePipelines,
-    /// The GitHub Actions environment, for Linux (including Docker), Windows and macOS builds.
-    GitHubActions,
-}
-
-impl CiEnv {
-    /// Obtains the current CI environment.
-    pub fn current() -> CiEnv {
-        if std::env::var("TF_BUILD").map_or(false, |e| e == "True") {
-            CiEnv::AzurePipelines
-        } else if std::env::var("GITHUB_ACTIONS").map_or(false, |e| e == "true") {
-            CiEnv::GitHubActions
-        } else {
-            CiEnv::None
-        }
-    }
-
-    pub fn is_ci() -> bool {
-        Self::current() != CiEnv::None
-    }
-
-    /// If in a CI environment, forces the command to run with colors.
-    pub fn force_coloring_in_ci(self, cmd: &mut Command) {
-        if self != CiEnv::None {
-            // Due to use of stamp/docker, the output stream of rustbuild is not
-            // a TTY in CI, so coloring is by-default turned off.
-            // The explicit `TERM=xterm` environment is needed for
-            // `--color always` to actually work. This env var was lost when
-            // compiling through the Makefile. Very strange.
-            cmd.env("TERM", "xterm").args(&["--color", "always"]);
-        }
-    }
-}
diff --git a/src/tools/build_helper/src/git.rs b/src/tools/build_helper/src/git.rs
deleted file mode 100644
index e9638206e67..00000000000
--- a/src/tools/build_helper/src/git.rs
+++ /dev/null
@@ -1,30 +0,0 @@
-use std::process::Command;
-
-/// Finds the remote for rust-lang/rust.
-/// For example for these remotes it will return `upstream`.
-/// ```text
-/// origin  https://github.com/Nilstrieb/rust.git (fetch)
-/// origin  https://github.com/Nilstrieb/rust.git (push)
-/// upstream        https://github.com/rust-lang/rust (fetch)
-/// upstream        https://github.com/rust-lang/rust (push)
-/// ```
-pub fn get_rust_lang_rust_remote() -> Result<String, String> {
-    let mut git = Command::new("git");
-    git.args(["config", "--local", "--get-regex", "remote\\..*\\.url"]);
-
-    let output = git.output().map_err(|err| format!("{err:?}"))?;
-    if !output.status.success() {
-        return Err("failed to execute git config command".to_owned());
-    }
-
-    let stdout = String::from_utf8(output.stdout).map_err(|err| format!("{err:?}"))?;
-
-    let rust_lang_remote = stdout
-        .lines()
-        .find(|remote| remote.contains("rust-lang"))
-        .ok_or_else(|| "rust-lang/rust remote not found".to_owned())?;
-
-    let remote_name =
-        rust_lang_remote.split('.').nth(1).ok_or_else(|| "remote name not found".to_owned())?;
-    Ok(remote_name.into())
-}
diff --git a/src/tools/build_helper/src/lib.rs b/src/tools/build_helper/src/lib.rs
deleted file mode 100644
index d3d2323db85..00000000000
--- a/src/tools/build_helper/src/lib.rs
+++ /dev/null
@@ -1,2 +0,0 @@
-pub mod ci;
-pub mod git;
diff --git a/src/tools/tidy/Cargo.toml b/src/tools/tidy/Cargo.toml
index ffedb4d5eb8..97d038da702 100644
--- a/src/tools/tidy/Cargo.toml
+++ b/src/tools/tidy/Cargo.toml
@@ -5,7 +5,6 @@ edition = "2021"
 autobins = false
 
 [dependencies]
-build_helper = { path = "../build_helper" }
 cargo_metadata = "0.14"
 regex = "1"
 miropt-test-tools = { path = "../miropt-test-tools" }
diff --git a/src/tools/tidy/src/lib.rs b/src/tools/tidy/src/lib.rs
index 186cd9bb11b..698e4850bea 100644
--- a/src/tools/tidy/src/lib.rs
+++ b/src/tools/tidy/src/lib.rs
@@ -48,7 +48,6 @@ pub mod errors;
 pub mod extdeps;
 pub mod features;
 pub mod mir_opt_tests;
-pub mod no_merge;
 pub mod pal;
 pub mod primitive_docs;
 pub mod style;
diff --git a/src/tools/tidy/src/main.rs b/src/tools/tidy/src/main.rs
index 65f0fe9743f..6714c63ee62 100644
--- a/src/tools/tidy/src/main.rs
+++ b/src/tools/tidy/src/main.rs
@@ -107,8 +107,6 @@ fn main() {
         check!(alphabetical, &compiler_path);
         check!(alphabetical, &library_path);
 
-        check!(no_merge, ());
-
         let collected = {
             drain_handles(&mut handles);
 
diff --git a/src/tools/tidy/src/no_merge.rs b/src/tools/tidy/src/no_merge.rs
deleted file mode 100644
index 362d6f6f4d7..00000000000
--- a/src/tools/tidy/src/no_merge.rs
+++ /dev/null
@@ -1,72 +0,0 @@
-//! This check makes sure that no accidental merge commits are introduced to the repository.
-//! It forbids all merge commits that are not caused by rollups/bors or subtree syncs.
-
-use std::process::Command;
-
-use build_helper::ci::CiEnv;
-use build_helper::git::get_rust_lang_rust_remote;
-
-macro_rules! try_unwrap_in_ci {
-    ($expr:expr) => {
-        match $expr {
-            Ok(value) => value,
-            Err(err) if CiEnv::is_ci() => {
-                panic!("Encountered error while testing Git status: {:?}", err)
-            }
-            Err(_) => return,
-        }
-    };
-}
-
-pub fn check(_: (), bad: &mut bool) {
-    let remote = try_unwrap_in_ci!(get_rust_lang_rust_remote());
-    let merge_commits = try_unwrap_in_ci!(find_merge_commits(&remote));
-
-    let mut bad_merge_commits = merge_commits.lines().filter(|commit| {
-        !(
-            // Bors is the ruler of merge commits.
-            commit.starts_with("Auto merge of") || commit.starts_with("Rollup merge of")
-        )
-    });
-
-    if let Some(merge) = bad_merge_commits.next() {
-        tidy_error!(
-            bad,
-            "found a merge commit in the history: `{merge}`.
-To resolve the issue, see this: https://rustc-dev-guide.rust-lang.org/git.html#i-made-a-merge-commit-by-accident.
-If you're doing a subtree sync, add your tool to the list in the code that emitted this error."
-        );
-    }
-}
-
-/// Runs `git log --merges --format=%s $REMOTE/master..HEAD` and returns all commits
-fn find_merge_commits(remote: &str) -> Result<String, String> {
-    let mut git = Command::new("git");
-    git.args([
-        "log",
-        "--merges",
-        "--format=%s",
-        &format!("{remote}/master..HEAD"),
-        // Ignore subtree syncs. Add your new subtrees here.
-        ":!src/tools/miri",
-        ":!src/tools/rust-analyzer",
-        ":!compiler/rustc_smir",
-        ":!library/portable-simd",
-        ":!compiler/rustc_codegen_gcc",
-        ":!src/tools/rustfmt",
-        ":!compiler/rustc_codegen_cranelift",
-        ":!src/tools/clippy",
-    ]);
-
-    let output = git.output().map_err(|err| format!("{err:?}"))?;
-    if !output.status.success() {
-        return Err(format!(
-            "failed to execute git log command: {}",
-            String::from_utf8_lossy(&output.stderr)
-        ));
-    }
-
-    let stdout = String::from_utf8(output.stdout).map_err(|err| format!("{err:?}"))?;
-
-    Ok(stdout)
-}